Buggy code:
public abstract class MarkupContainer extends Component { private static final Log log = LogFactory . getLog ( MarkupContainer . class ) ; private static final Map markupCache = new HashMap ( ) ; private static final int MINIMAP_MAX_ENTRIES = 8 ; private static final boolean optimizeChildMapsForSpace = false ; private Map childForId = Collections . EMPTY_MAP ; private transient MarkupStream markupStream ; private class ComponentIterator implements Iterator { private Component component ; private Iterator iterator ; public ComponentIterator ( Iterator iterator ) { } public boolean hasNext ( ) { } public Object next ( ) { } public void remove ( ) { } } public MarkupContainer ( final String id ) { } public MarkupContainer ( final String id , IModel model ) { } public MarkupContainer add ( final Component child ) { } public final boolean contains ( final Component component , final boolean recurse ) { } public final Component get ( final String path ) { } public void internalBeginRequest ( ) { } public void internalEndRequest ( ) { } public final Iterator iterator ( ) { } public void remove ( final String id ) { } public void removeAll ( ) { } public MarkupContainer replace ( final Component child ) { } public final int size ( ) { } public String toString ( ) { final StringBuffer buffer = new StringBuffer ( ) ; <START_BUG> buffer . append ( "[" ) ; <END_BUG> buffer . append ( super . toString ( ) ) ; if ( ( markupStream ) != null ) { buffer . append ( ( ",<seq2seq4repair_space>markupStream<seq2seq4repair_space>=<seq2seq4repair_space>" + ( markupStream ) ) ) ; } if ( ( ( childForId ) != null ) && ( ( childForId . size ( ) ) != 0 ) ) { buffer . append ( ( ",<seq2seq4repair_space>children<seq2seq4repair_space>=<seq2seq4repair_space>" + ( childForId . values ( ) ) ) ) ; } buffer . append ( ']' ) ; return buffer . toString ( ) ; } public final Object visitChildren ( final Class c , final IVisitor visitor ) { } public final Object visitChildren ( final IVisitor visitor ) { } protected final MarkupStream findMarkupStream ( ) { } protected final MarkupStream getMarkupStream ( ) { } protected String getMarkupType ( ) { } protected void onComponentTagBody ( final MarkupStream markupStream , final ComponentTag openTag ) { } protected void onRender ( ) { } protected final void renderAssociatedMarkup ( final String openTagName , final String exceptionMessage ) { } protected final void renderComponentTagBody ( final MarkupStream markupStream , final ComponentTag openTag ) { } protected boolean resolveComponent ( final MarkupStream markupStream , final ComponentTag tag ) { } protected final void setMarkupStream ( final MarkupStream markupStream ) { } final void autoAdd ( final Component component ) { } final Markup getAssociatedMarkup ( ) { } final MarkupStream getAssociatedMarkupStream ( ) { } final boolean hasAssociatedMarkup ( ) { } final void renderAll ( final MarkupStream markupStream ) { } private Markup loadMarkup ( final Application application , final String key , final IResource markupResource ) throws IOException , ParseException , ResourceNotFoundException { } private Markup loadMarkupAndWatchForChanges ( final String key , final IResource markupResource ) { } private String markupKey ( ) { } private void optimize ( ) { } private void renderNext ( final MarkupStream markupStream ) { } }

Fix:
buffer . append ( "[MarkupContainer<seq2seq4repair_space>super<seq2seq4repair_space>=<seq2seq4repair_space>" ) ;